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From: Mike Kravetz <mike.kravetz@oracle.com>
To: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>, Minchan Kim <minchan@kernel.org>,
	David Hildenbrand <david@redhat.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Shakeel Butt <shakeelb@google.com>,
	Oscar Salvador <osalvador@suse.de>,
	Muchun Song <songmuchun@bytedance.com>,
	David Rientjes <rientjes@google.com>,
	Miaohe Lin <linmiaohe@huawei.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Matthew Wilcox <willy@infradead.org>,
	HORIGUCHI NAOYA <naoya.horiguchi@nec.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
	Waiman Long <longman@redhat.com>, Peter Xu <peterx@redhat.com>,
	Mina Almasry <almasrymina@google.com>,
	Hillf Danton <hdanton@sina.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Barry Song <song.bao.hua@hisilicon.com>,
	Will Deacon <will@kernel.org>
Subject: Re: [PATCH 1/8] mm: cma: introduce cma_release_nowait()
Date: Mon, 29 Mar 2021 15:27:00 -0700	[thread overview]
Message-ID: <0b2afe77-f7fb-4c44-2861-bdf4085fe9e8@oracle.com> (raw)
In-Reply-To: <YGGF4tFogzETutOR@dhcp22.suse.cz>

On 3/29/21 12:46 AM, Michal Hocko wrote:
> On Fri 26-03-21 14:32:01, Mike Kravetz wrote:
> [...]
>> - Just change the mutex to an irq safe spinlock.
> 
> Yes please.
> 
>>   AFAICT, the potential
>>   downsides could be:
>>   - Interrupts disabled during long bitmap scans
> 
> How large those bitmaps are in practice?
> 
>>   - Wasted cpu cycles (spinning) if there is much contention on lock
>>   Both of these would be more of an issue on small/embedded systems. I
>>   took a quick look at the callers of cma_alloc/cma_release and nothing
>>   stood out that could lead to high degrees of contention.  However, I
>>   could have missed something.
> 
> If this is really a practical concern then we can try a more complex
> solution based on some data.
> 

Ok, I will send v2 with this approach.  Adding Barry and Will on Cc: as
they were involved in adding more cma use cases for dma on arm.

-- 
Mike Kravetz

  reply	other threads:[~2021-03-29 22:34 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-25  0:28 [PATCH 0/8] make hugetlb put_page safe for all calling contexts Mike Kravetz
2021-03-25  0:28 ` [PATCH 1/8] mm: cma: introduce cma_release_nowait() Mike Kravetz
2021-03-25  9:39   ` Oscar Salvador
2021-03-25  9:45   ` Michal Hocko
2021-03-25  9:54     ` Oscar Salvador
2021-03-25 10:10       ` Michal Hocko
2021-03-25 10:11     ` Michal Hocko
2021-03-25 10:13       ` David Hildenbrand
2021-03-25 10:17       ` Oscar Salvador
2021-03-25 10:24         ` Michal Hocko
2021-03-25  9:56   ` David Hildenbrand
2021-03-25 10:22     ` Michal Hocko
2021-03-25 16:56       ` Mike Kravetz
2021-03-25 17:15         ` David Hildenbrand
2021-03-25 20:12           ` Minchan Kim
2021-03-25 23:19             ` Roman Gushchin
2021-03-25 23:49               ` Mike Kravetz
2021-03-26 21:32                 ` Mike Kravetz
2021-03-29  7:46                   ` Michal Hocko
2021-03-29 22:27                     ` Mike Kravetz [this message]
2021-03-25  0:28 ` [PATCH 2/8] mm: hugetlb: don't drop hugetlb_lock around cma_release() call Mike Kravetz
2021-03-25  0:28 ` [PATCH 3/8] hugetlb: add per-hstate mutex to synchronize user adjustments Mike Kravetz
2021-03-25 10:47   ` Michal Hocko
2021-03-25 12:29   ` Oscar Salvador
2021-03-26  1:52   ` Miaohe Lin
2021-03-25  0:28 ` [PATCH 4/8] hugetlb: create remove_hugetlb_page() to separate functionality Mike Kravetz
2021-03-25 10:49   ` Michal Hocko
2021-03-26  2:10   ` Miaohe Lin
2021-03-26 19:57     ` Mike Kravetz
2021-03-27  1:40       ` Miaohe Lin
2021-03-27  6:36   ` [External] " Muchun Song
2021-03-27  6:36     ` Muchun Song
2021-03-25  0:28 ` [PATCH 5/8] hugetlb: call update_and_free_page without hugetlb_lock Mike Kravetz
2021-03-25 10:55   ` Michal Hocko
2021-03-25 17:12     ` Mike Kravetz
2021-03-25 19:39       ` Michal Hocko
2021-03-25 20:33         ` Mike Kravetz
2021-03-27  6:54   ` [External] " Muchun Song
2021-03-27  6:54     ` Muchun Song
2021-03-28 21:40     ` Mike Kravetz
2021-03-25  0:28 ` [PATCH 6/8] hugetlb: change free_pool_huge_page to remove_pool_huge_page Mike Kravetz
2021-03-25 11:06   ` Michal Hocko
2021-03-25 17:29     ` Mike Kravetz
2021-03-25  0:28 ` [PATCH 7/8] hugetlb: make free_huge_page irq safe Mike Kravetz
2021-03-25 11:21   ` Michal Hocko
2021-03-25 17:32     ` Mike Kravetz
2021-03-27  7:06   ` [External] " Muchun Song
2021-03-27  7:06     ` Muchun Song
2021-03-29  7:49     ` Michal Hocko
2021-03-29 22:44       ` Mike Kravetz
2021-03-25  0:28 ` [PATCH 8/8] hugetlb: add lockdep_assert_held() calls for hugetlb_lock Mike Kravetz
2021-03-25 11:22   ` Michal Hocko
2021-03-26  2:12   ` Miaohe Lin
2021-03-27  8:14   ` [External] " Muchun Song
2021-03-27  8:14     ` Muchun Song
2021-03-26  1:42 ` [PATCH 0/8] make hugetlb put_page safe for all calling contexts Miaohe Lin
2021-03-26 20:00   ` Mike Kravetz

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